Isfahan has a population of approximately 1.6 million,[4] making it the third largest city in Iran after Tehran and Mashhad.

Isfahan is an important city as it is located at the intersection of the two principal north–south and east–west routes that traverse Iran. It was once one of the largest cities in the world. It flourished from 1050 to 1722, particularly in the 16th and 17th centuries under the Safavid dynasty when it became the capital of Persia for the second time in its history. Even today the city retains much of its past glory. It is famous for its Persian–Islamic architecture, having many beautiful boulevards, covered bridges, palaces, mosques, and minarets, and the city also has many historical buildings, monuments, paintings and artefacts. The fame of Isfahan led to the Persian pun and proverb "Esfahān nesf-e- jahān ast": Isfahan is half (of) the world.[5]

"Isfahan" is derived from Middle PersianSpahān. Spahān is attested in various Middle Persian seals and inscriptions, including that of Zoroastrian Magi Kartir,[6] and is also the Armenian name of the city (Սպահան). The present-day name is the Arabicized form of Ispahan (unlike Middle Persian, and similar to Spanish, New Persian does not allow initial consonant clusters such as sp[7]). The region appears with the abbreviation GD (Southern Media) on Sasanian numismatics. In Ptolemy's Geographia it appears as Aspadana, translating to "place of gathering for the army". It is believed that Spahān derives from spādānām "the armies", Old Persian plural of spāda (from which derives spāh 'army' and spahi (soldier – lit. of the army) in Middle Persian).

What was to become the city of Isfahan in later historical periods probably emerged as a locality and settlement that gradually developed over the course of the Elamite civilisation (2700–1600 BCE).

Under Median rule, this commercial entrepôt began to show signs of a more sedentary urbanism, steadily growing into a noteworthy regional centre that benefited from the exceptionally fertile soil on the banks of the Zayandehrud River in a region called Aspandana or Ispandana.

Once Cyrus the Great (reg. 559–529 BCE) had unified Persian and Median lands into the Achaemenid Empire (648–330 BCE), the religiously and ethnically diverse city of Isfahan became an early example of the king's fabled religious tolerance. It was Cyrus who, having just taken Babylon, made an edict in 538 BCE, declaring that the Jews in Babylon could return to Jerusalem (see Ezra ch. 1). Now it seems that some of these freed Jews settled in Isfahan instead of returning to their homeland. The 10th-century Persian historian Ibn al-Faqih wrote:

"When the Jews emigrated from Jerusalem, fleeing from Nebuchadnezzar, they carried with them a sample of the water and soil of Jerusalem. They did not settle down anywhere or in any city without examining the water and the soil of each place. They did all along until they reached the city of Isfahan. There they rested, examined the water and soil and found that both resembled Jerusalem. Thereupon they settled there, cultivated the soil, raised children and grandchildren, and today the name of this settlement is Yahudia."[8]

The Parthians in the period 250–226 BCE continued the tradition of tolerance after the fall of the Achaemenids, fostering the Hellenistic dimension within Iranian culture and the political organisation introduced by Alexander the Great's invading armies. Under the Parthians, Arsacid governors administered the provinces of the nation from Isfahan, and the city's urban development accelerated to accommodate the needs of a capital city.

Isfahan at the end of the 6th century (top), consisting of two separate areas of Sassanid Jay and Jewish Yahudia. At 11th century (bottom), these two areas are completely merged.

The next empire to rule Persia, the Sassanids (226–652 CE), presided over massive changes in their realm, instituting sweeping agricultural reform and reviving Iranian culture and the Zoroastrian religion. Both the city and region were then called by the name Aspahan or Spahan. The city was governed by a group called the Espoohrans, who came from seven noble and important Iranian royal families. Extant foundations of some Sassanid-era bridges in Isfahan suggest that the Sasanian kings were fond of ambitious urban planning projects. While Isfahan's political importance declined during the period, many Sassanid princes would study statecraft in the city, and its military role developed rapidly. Its strategic location at the intersection of the ancient roads to Susa and Persepolis made it an ideal candidate to house a standing army, ready to march against Constantinople at any moment. The words 'Aspahan' and 'Spahan' are derived from the Pahlavi or Middle Persian meaning 'the place of the army'.[9] Although many theories have been mentioned about the origin of Isfahan, in fact little is known of it before the rule of the Sasanian dynasty (c. 224 – c. 651 CE). The historical facts suggest that in the late 4th and early 5th centuries, Queen Shushandukht, the Jewish consort of Yazdegerd I (reigned 399–420) settled a colony of Jews in Yahudiyyeh (also spelled Yahudiya), a settlement 3 km northwest of the Zoroastrian city of Gabae (its Achaemid and Parthian name; Gabai was its Sasanic name, which was shortened to Gay (Arabic 'Jay') that was located on the northern bank of the Zayanderud River. The gradual population decrease of Gay (Jay) and the simultaneous population increase of Yahudiyyeh and its suburbs after the Islamic conquest of Iran resulted in the formation of the nucleus of what was to become the city of Isfahan. The words "Aspadana", "Ispadana", "Spahan" and "Sepahan", all from which the word Isfahan is derived, referred to the region in which the city was located.

Isfahan and Gay were both circular in design, a characteristic of Parthian and Sasanian cities.[10]

When the Arabs captured Isfahan in 642, they made it the capital of al-Jibal ("the Mountains") province, an area that covered much of ancient Media. Isfahan grew prosperous under the Persian Buyid (Buwayhid) dynasty, which rose to power and ruled much of Iran when the temporal authority of the Abbasid caliphs waned in the 10th century. The Turkish conqueror and founder of the Seljuq dynasty, Toghril Beg, made Isfahan the capital of his domains in the mid-11th century; but it was under his grandson Malik-Shah I (r. 1073–92) that the city grew in size and splendour.[11]

After the fall of the Seljuqs (c. 1200), Isfahan temporarily declined and was eclipsed by other Iranian cities such as Tabriz and Qazvin.

During his visit in 1327, Ibn Battuta noted that "The city of Isfahan is one of the largest and fairest of cities, but it is now in ruins for the greater part."[12] It regained its importance during the Safavid period (1501–1736). The city's golden age began in 1598 when the Safavid ruler Shah Abbas I (reigned 1588–1629) made it his capital and rebuilt it into one of the largest and most beautiful cities in the 17th century world. In 1598 Shah Abbas the Great moved his capital from Qazvin to the more central Isfahan; he name it Ispahān (New Persian) so that it wouldn't be threatened by the Ottomans. This new status ushered in a golden age for the city, with architecture and Persian culture flourishing. In the 16th and 17th centuries, thousands of deportees and migrants from the Caucasus, that Abbas and other Safavid rulers had permitted to emigrate en masse, settled in the city. So now the city had enclaves of Georgian, Circassian, and Daghistani descent.[13] Engelbert Kaempfer, who dwelt in Safavid Persia in 1684–85, estimated their number at 20,000.[13][14] During the Safavid era, the city contained a very large Armenian community as well. As part of Abbas's forced resettlement of peoples from within his empire, he resettled as many as 300,000 Armenians[15][16]) from near the unstable Safavid-Ottoman border, primarily from the very wealthy Armenian town of Jugha (also known as Old Julfa) in mainland Iran.[16] In Isfahan, he ordered the foundation of a new quarter for these resettled Armenians from Old Julfa, and thus the Armenian Quarter of Isfahan was named New Julfa.[15][16] Today, the New Jolfa district of Isfahan remains a heavily Armenian-populated district, with Armenian churches and shops, the Vank Cathedral being especially notable for its combination of Armenian Christian and Iranian Islamic elements. It is still one of the oldest and largest Armenian quarters in the world. Following an agreement between Shah Abbas I and his Georgian subject Teimuraz I of Kakheti ("Tahmuras Khan"), whereby the latter submitted to Safavid rule in exchange for being allowed to rule as the region’s wāli (governor) and for having his son serve as dāruḡa ("prefect") of Isfahan in perpetuity, the Georgian prince converted to Islam and served as governor.[13] He was accompanied by a troop of soldiers,[13] some of whom were Georgian Orthodox Christians.[13] The royal court in Isfahan had a great number of Georgian ḡolāms (military slaves), as well as Georgian women.[13] Although they spoke both Persian and Turkic, their mother tongue was Georgian.[13] During Abbas's reign, Isfahan became very famous in Europe, and many European travellers made an account of their visit to the city, such as Jean Chardin. This prosperity lasted until it was sacked by Afghan invaders in 1722 during a marked decline in Safavid influence.

In the early years of the 19th century, efforts were made to preserve some of Ifsahan's archeologically important buildings. The work was started by Mohammad Hossein Khan during the reign of Fath Ali Shah.[17]

In the 20th century, Isfahan was resettled by a very large number of people from southern Iran, firstly during the population migrations at the start of the century, and again in the 1980s following the Iran–Iraq War.

Today, Isfahan produces fine carpets, textiles, steel, handicrafts, and traditional foods including sweets. There are nuclear experimental reactors as well as facilities for producing nuclear fuel (UCF) within the environs of the city. Isfahan has one of the largest steel-producing facilities in the region, as well as facilities for producing special alloys. Mobarakeh Steel Company is the biggest steel producer in the whole of the Middle East and Northern Africa, and it is the biggest DRI producer in the world.[18] The Isfahan Steel Company was the first manufacturer of constructional steel products in Iran, and it remains the largest such company today.[19]

There are a major oil refinery and a large airforce base outside the city. HESA, Iran's most advanced aircraft manufacturing plant, is located just outside the city.[20][21] Isfahan is also attracting international investment,[22] especially in the Isfahan City Center[23] which is the largest shopping mall in Iran and the fifth largest in the world.[24]

The city is located in the lush plain of the Zayanderud River at the foothills of the Zagros mountain range. The nearest mountain is Mount Soffeh (Kuh-e Soffeh), just south of the city. No geological obstacles exist within 90 kilometres (56 miles) north of Isfahan, allowing cool winds to blow from this direction. Situated at 1,590 metres (5,217 ft) above sea level on the eastern side of the Zagros Mountains, Isfahan has an arid climate (KöppenBWk). Despite its altitude, Isfahan remains hot during the summer, with maxima typically around 35 °C (95 °F). However, with low humidity and moderate temperatures at night, the climate is quite pleasant. During the winter, days are mild while nights can be very cold. Snow has occurred at least once every winter except 1986/1987 and 1989/1990.[25] The Zayande River starts in the Zagros Mountains, flowing from the west through the heart of the city, then dissipates in the Gavkhooniwetland.

Air pollution is one of the major environmental issues in Isfahan. Due to an increase in the number of cars in the city, thermal power plants, petrochemical complexes and the oil refinery in the west of the city, air pollution levels have increased markedly in the second half of the 20th century. With the introduction of national environment levels for heavy industry, industrial pollution has been reduced in recent years. However, the air quality in the city is far below world norms. Indeed, Isfahan has the highest air pollution index of all the major cities in Iran. This is thought to be partly due to its climate and geography.[29]

The bridges on the Zayanderud river comprise some of the finest architecture in Isfahan. The oldest bridge is the Shahrestan bridge, whose foundations were built by the Sasanian Empire (3rd–7th century Sassanid era); it was repaired during the Seljuk period. Further upstream is the Khaju bridge, which was built by Shah Abbas II in 1650. It is 123 metres (404 feet) long with 24 arches, and also serves as a sluice gate.

Another bridge is the Choobi (Joui) bridge, which was originally an aqueduct to supply the palace gardens on the north bank of the river. Further upstream again is the Si-o-Seh Pol or bridge of 33 arches. Built during the reign of Shah Abbas the Great, it linked Isfahan with the Armenian suburb of New Julfa. It is by far the longest bridge in Isfahan at 295 m (967.85 ft).

Over the past decade, Isfahan's internal highway network has been undergoing major expansion. Much care has been taken to prevent damage to valuable, historical buildings. Modern freeways connect the city to the country's major cities, including the capital Tehran (length approximately 400 km) to the north and Shiraz (200 km) to the south. Highways also service satellite cities surrounding the metropolitan area.[36]

^ abAslanian, Sebouh (2011). From the Indian Ocean to the Mediterranean: The Global Trade Networks of Armenian Merchants from New Julfa. California: University of California Press. p. 1. ISBN978-0520947573.